The person spoke Friday on the condition of anonymity because the team has not disclosed a diagnosis.
Brackett was injured during Thursday night's loss at Green Bay when he appeared to hit his hand on the helmet of teammate Philip Wheeler. He is the Colts' defensive captain and signed a five-year, $33 million contract in March.
Brackett is not likely to play next Thursday against the Bengals because the Colts traditionally bench most of their starters in the preseason finale.
Copyright 2010 by The Associated Press
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